It's entirely acceptable to raise the question of the quality of the source if it's unknown. I, for one, know nothing about the World Socialist Web Site, or whether they have a habit of pushing stories with glaring omissions, unfounded additions or in the worst case, plain falsehoods. I do know to some degree about a fair number of larger news organizations, and while none are perfect, I trust a number of them to not completely violate the faith many people have in them (as that would be counterproductive to their business).

If the WSWS is respectable, presumably it will have a history of handling stories responsibly, and someone here can vouch for that. If nobody here knows, then it is useful to note that so people can investigate before assuming truth.